ROCK DEFORMATION

• force applied per unit area

  stress
• corresponding changes

  strain
• also know as deformation

  strain
• this developed when brittle rocks deform so much that they break

  fault types
• 3 types of stress

  tensional

  compressional

  shear
• this type of stress cause lengheting

  tension
• causes shortening

  compression
• cause tearing and shearing

  shear
• what causes normal faults?

  tension
• what causes reverse faults?

  compressional
• compresssional stresses usually forms what

  reverse faults

  thrust faults
• what usually forms when shear stress is applied?

  strike slip fault
• refers to the line formed by the intersection of a horizontal plane and an inclined surface

  strike
• is the angle between that horizontal plane (such as the top of this block) and the tilted surface (the geologic contact between the tilted layers). 

  dip
• used to describe the

  rock bed, fault,

  fracture, cuestas,

  igneous dikes, and

  sills

  strike and dip
• types of deformation

  elastic

  ductile

  brittle
• return to their original shape and size

  elastic
•  results in rocks being broken apart, causing a loss of coherence

  brittle
• does not go back to original form when stress applied

  ductile
• what type of deformation usually form folds

  ductile deformation
• type of fold where axial plane is vertical

  symmetrical folds
• type of fold where beds in one limb dip more steeply than those in the others

  asymmetrical folds
• type of fold where both limbs dip in same direction but one limb has been tilted beyond vertical

  overturned folds
• fold shapes

  laro hhahahahah love u

  A) parallel fold

  B) concentric fold

  C) chevron fold

  D) kink band

  E) similar fold

  F) disharmonic fold

  G) box fold

  
• upwarping produces a dome
• downwarping produces a basin
• upwarping have the oldest strata
• downwarping has the youngest strata
• brittle deformation results in faults and joints
• left lateral strike-slip fault

  sinistral
• right lateral strike-slip fault

  dextral
• example of sinistral


  philippine fault system
• example of dextral

  san andreas fault
• 3 types of faults that results in brittle deformation

  strike-slip faults

  dip-slip faults

  oblique-slip faults
• mostly have steep slopes

  reverse fault
• gentle slopes fault

  thrust fault
• Normal faults: Blocks of rock move downward relative to each other.

  Reverse faults: Blocks of rock move upward relative to each other

  Strike-slip faults: Blocks of rock move horizontally past each other
• two types of oblique-slip fault

  horst

  graben
• philippine fault is first proposed by willis
• master fault - repetti

  visayan rift - willis